How to make thorns (Crown of Thorns)?
You may create the thorns fast using some modifiers.


Add two (or more) cylinders and place them next to each other. Model the spikes. Join cylinders with Ctrl+J in Object Mode. Press Shift+C to place the cursor in the center, then press Shift+Ctrl+Alt+C-->Origin to 3D Cursor. Press Ctrl+A-->Apply Rot&amp;Scale. Add a Bezier Circle also (Add-->Curve-->Circle).


Select cylinders and add the Subsurf and Simple Deform modifiers. Add some subdivisions in Subsurf panel. Smooth the object using smooth shading in the Transform panel of the Tool Shelf (T). Set the Simple Deform type to Twist and set the angle to 180 degrees (or other value depending on your preferences).


Next add an Array modifier. Set its Z offset to 1.000. Check the Merge checkbox. Increase the Count number. Then add a Curve modifier and set the Bezier Circle as a target.


Remember of the proper order of the modifiers. This is the key to make it work as it should.


Finally select the Bezier Circle and go to the Curve header. Check the Stretch and Bounds Clamp checkboxes. 


Try to add more cylinders and randomise the spikes positions and directions for the different results. You may also apply the modifiers (without Subsurf) at the end and randomize the size, shape and direction of each spike to make it look more realistic.